Recent experiments have made it necessary to introduce a significant amount of channel interaction into the multiple spatial frequency channel model. Such interaction destroys the frequency specificity originally attributed to the channels, and under some conditions, makes the behavior of channels depend on extremely general properties of a pattern. These problems for the channel model have led us to a new analysis of experiments on threshold elevation and perceived frequency shift after adaptation to composite gratings, and experiments on sub-threshold additivity. We argue that what lies behind these experiments, normally used to support the channel hypothesis, may actually have to do with principles of supra-threshold pattern vision, intimately tied up with actual pattern appearance and the sensitivity of appearance to a physical change of the stimulus, and is not connected to any fundamental process of spatial frequency analysis going on in human vision. Threshold elevation and perceived frequency shift experiments involving classes of adaptation patterns with specially chosen spatial frequency content, as well as experiments analyzing relationships between supra-threshold gratings according to perceivable differences in form and contrast will be done to test sharply both the conventional channel model and our new point of view.